Grease composition



P tented Apr-: 1940. Y

. TED STATES: PTATENT OFFICE.

oaaasn comosrriou Emmett S. Carmichael, Jackson Heights, N. Y., andGeorge M. Hain, Montclair, N. J., asslgnors to Socony-Vacuum OilCompany, Incorporated,

New York, N. Y., a corporation of New York No Drawing.

Application February 23, 1939,

Serial No. 257,958

13 Claims.

This invention is directed to improvements in lime base greases, that isto grease compositions consisting basically of mineral oils in admixturewith lime soaps or with a suflicient pro- 5 portion of lime soap to havethe characteristics usually attributed to lime base greases. Suchgreases in their usual form constitute the usual commercial cup greasesand are useful for unexacting services at low temperatures. Lime basegreases of the normal type are not capable of use at elevatedtemperatures since they lose stability at temperatures in excess ofabout 175 F. and are entirely unstable at temperatures near or above thenormal boiling point of water 5 due to excessive loss of moisture andconsequent disintegration of the grease.

This invention has for its object the provision of novel and improvedlime base greases characterized by stability at temperatures well noabove those at which normal 'type lime base greases are applicable.

This invention is based upon the discovery that by compounding inthelime base grease small controlled amounts of certain ingredientsheretofore novel in lime base greases, greases are obtained which, whilepossessed of the usual desirable characteristics of lime base greasesare additionally possessed of stability at temperatures far in excess ofthe upper temperature limits at which normal types of lime base greasesare capable of being applied.

This invention is further based upon the discovery that when lime basegreases containing such ingredients are dehydrated in manufacture stillfurther gains in ability to resist high temperature are effected.

This invention is based upon the discovery that by the addition to limebase greases and to those mixed lime-soda base greases in which limesoaps predominate and which substantially retain the characteristics oflime base greases, of a small amount of the calcium salts of low molec-5 ular weight organic acids either alone or in combination withcontrolled small amounts of mentan wax, there results a grease havingtemperature stability greatly enhanced over that of the usual lime basegreases.

As an example of a typical formula for the improved grease, thefollowing formula is given in which per cents are by weight:

Exmrml I -Per cent Hydrofol fatty acids... 5.5 Cottonseed fatty acids5.5 Refined montan wax 2.0

Low molecular weight organic acids having the general formula cnHznoil,where n is This grease, compounded according to the above formula iscontrasted with a conventional lime base grease formula, which is asfollows:

Conventional lime base grease formula Per cent Tallow 16.0 Lime flour2.4 S. U. V. 100 F. mineral oil 81.6

"In the above formula the 100" paraffin oil is a lightmineral oil having100" Saybolt viscosity at 100 F. It will be understood that inaccordance with practise, other oils may be substituted for this oil,dependent upon the nature of the lime-base grease desired. Lime flour isthe usual product of commerce. and tallow, where mentioned, are usualproducts of commerce. Hydrofol fatty acids are fatty acids derived fromhydrogenated fish oils appearing in the trade under several names, oneof which is Hydrofol. Montan wax is the ordinary crude or refined montanwax of com- Cottonseed fatty acids 7 merce, except for greases of thecold sett type illustrated by Example I, where refined montan wax shouldbe used.

The greases in Examples I and II, exhibited very marked degrees ofimprovement in heat stability over the conventional lime base grease.For example, two tests are used to show these properties.

The first test is a proposed method of test for dropping point oflubricating greases, described on pages 14 and 15 of the September, 1937issue of the A. S. T. M. Standards of Petroleum Products and Lubricants,Prepared by Committee D-2. This dropping point test consists essentiallyof placing the grease within a grease cup which has an open orifice ofspecified diameter at the bottom and is surrounded by a heating jacket.Upon raising the temperature gradually, the temperature is observed atwhich the first drop of grease passes through the orifice.

This test gives information as to when the grease is softened, byheating, to a point of leakage and dropping through an orifice ofspecified diameter. Although the test is made on a grease sample in aperfectly quiescent state and, therefore, may not represent the actualservice conditions, it gives valuable indication as to the consistencywhich may be expected in grease feeding devices at elevated temperaturesand which, in turn, has a bearing on the consumption of the grease.

The second test is conducted in the socalled B. E. C. grease testingmachine, developed by the Bearing Engineers Committee of theAnti-Friction Bearing Manufacturers Association. This machine has beendeveloped to study the structural stability of greases when agitated ina working ball bearing under specified conditions at known temperatures.Essentially, it is a ball bearing assembly operated at 3450 R. P. M. bya vertical motor and suspended in an oil bath, the temperature of whichcan be conveniently maintained at any level up to 300 F. The inner raceof the bearing is mounted on the extension spindle of the motor, and theouter race can be rigidly set in a grease cup. This cup is free to turnwith the bearing to allow torque measurements. A known amount of greaseis packed into the bearing and around the shaft. The bearing is shieldedby a plate on the bottom side with a small circular clearance betweenthe shield and the outer race. Any leakage of oil or molten greasethrough this clearance is collected on the bottom of the grease cup andcan be quantitatively determined. The initial test is conducted at Bil-F., and subsequent tests are made at F., 180 F., and 220 F. as required,the duration of each being 20 minutes. During all of these tests,separation of oil, change of structure, channelling, and aeration arenoted, in addition to the torque readings. The B. E. C. tester isvaluable for predicting the suitability of greases for ball bearinglubrication at elevated temperatures.

Exemplary of the increased stability of greases made in accordance withthis disclosure are the following results:

1. Using a grease compounded according-to Example I, in the proposed A.S. T. M. drop point determination, this grease was found to drop atapproximately 285 F., whereas a conventional lime base grease of aboutthe same consistency, drops at approximately 212 F.

2. Using the B. E. C. machine, the grease of Example I was compared witha conventional lime base grease, with the following results:

Experimental Conventional lime base grease (Example 1 (#4 cup grade)Temp Time of aga Temp Time of #3: F. test me F. test hum Minutes Minnie:80 20 None.... 80 20 None.

150 20 do-- Z) Do.

20 Trace- 180 20 10.

220 20 6 220 20 Cup was full.

Approximately 30%. The machine is not designed to measure higherleakages.

A grease prepared in accordance with the above formulation shows a totalleakage of approximately 8% when tested in the B. E. C.

machine for 3 hours at 180 F. and 1 hour at 220 F. A conventional limebase grease of approximately the same consistency (#4 cup grade) willbecome semi-fluid and the sample will flow thru and out of the bearingunder these conditions.

Additional comparative tests in the B. E. 0. machine, between theconventional grease set forth above in this specification and the greasefor Example II are as follows:

Percent total leakage Temp., F. Duration Conventional Example II NoneNone. Full cup. Do

'30 plus. The machine is not designed to measure higher leakages.

It will be noted that the conventional grease which showed excessiveleakage from the bearing after 20 minutes 150 F., was improved by theaddition of calcium acetate. to the point of satisfactory service 180 F.

A highly stable form of lime base grease results from a modifiedtreatment of a grease containing the same novel ingredients. By suchmodifications, a similar lime base grease may be prepared which does notchange its structure or consistency at elevated temperatures in theneighborhood of 300 F., even after prolonged use.

An exemplary formula for such a high temperature lime base grease isgiven below:

ExmLs III Per cent Hydrogenated fatty acids 5.5 Cottonseed fatty acids5.5 Refined or crude montan wax 4.0 Low molecular weight organic acidshaving the general formula CnHZnOB, where n is preferably 6 or less, e.g., acetic acid 4.0 Lime flour; 4.6

100 Sec. paraflln oil 76.4

- portions of ingredients, other Experimental grease (Example III) Timeof Total leakage, test percent Minute:

Total leakage,

Time of Temp., F. t percent est Minutes 20 Cup was full.

Approximately 30%. .The machine is not designed to measure higherleakages.

It will be noted that the greases according to the improved formulacontain montan wax. This montan wax is of significance in two respects.In the first place, in the presence of montan wax, all of thecomplements can be combined into the finished product in one operation,whereas attempts to incorporate the calcium acetate without montan waxhave been found to require a twostep operation in which calcium acetateis incorporated into an already prepared lime base grease. In the secondplace, the combined use of montan wax and low molecular weight organicacids results in improvements not attainable with either of thesecomponents alone.

That enhanced properties arise from the presence of calcium acetatewhich are not secured by the addition of montan wax alone is evident.

which is seen to be essentially the same as the conventional greaseexcept for the addition of montan wax, when tested in the B. E. 0.machine, was found to have leakage characteristics the same 'as theconventional formula. Some improved characteristics do follow, however,from the addition of montan wax which unquestionably assists in thestability of the entire combination.

Another outstanding feature of some forms of this product, asillustrated byExample I, is their ease of manufacture. This form can beprepared at temperatures below F. by simply mixing the lime "s1urry withthe oil-acid mixture and stirring until homogeneous. It, therefore,offers possibilities for continuous grease manufacture.

It will, of course, be realized that various proportions of the variousingredients may be used for the compounding of greases of varyingcharacteristics within the field defined by this disclosure. In suchvaried compositions the prothan the oil to be used, are as follows:

1. Less than 30% of fatty acids, glycerides or mixtures thereof, thepreferred range being from of such constituents.

2.'Less than 10% of calcium acetate or its equivalent, the minimumamount being approximately 0.2% and the preferred amounts being from0.5% to 5.0%.

3. Less than 7% of montan wax, the preferred amount being one to fivepercent.

We claim:

1. An improved lime base grease composition characterized by stabilityat temperatures inexcess of 200 F. comprising lubricatingoiland limesoaps of fatty acids and in addition thereto a small proportion of thecalcium salt of a monobasic fatty acid having not more than 6 carbonatoms.

2. An improved lime base grease composition characterized by stabilityat temperatures inexcess of 200 F. comprising lubricating oil and limesoaps of fatty acids and in addition thereto a small proportion ofcalcium acetate.

3. An improved lime base grease composition characterized by stabilityat temperatures in excess of 200 F. comprising lubricating oil and limesoaps of fatty acids and in addition thereto small proportions ofcalcium soaps of montan wax acids and of monobasic fatty acids havingnot more than 6 carbon atoms.

4. An improved lime base grease composition characterized by stabilityat temperatures in excess-of 200 F. comprising lubricating oil and limesoaps of fatty acids and in addition thereto small proportions ofcalcium'salts of acetic acid v and of montan wax acids.

5. An improved lime base grease composition characterized by stabilityat temperatures in excess of 200 F. comprising lubricating oil and limesoaps of high molecular weight fatty acids and'a small proportion, notover about 5%, of the calcium salt of a monobasic fatty acid havin notover 6 carbon atoms.

6. An improved lime base grease composition characterized by stabilityat temperatures in excess of 200 F. comprising lubricating oil and limesoaps of high molecular weight fatty acids and a small proportion, notover about 5%, of the calcium salt of acetic acid.

7. An improved lime base grease composition characterized by stabilityat temperatures in excess of 200 F. comprising lubricating oil and limesoaps of high molecular weight fatty acids to which have been added notover about 5% of calcium acetate and not over about 7% of montan wax.

8. Improved lime base greases characterized bystability at temperaturesin excess of 200 F. formed by compounding together from 5 to 20% of highmolecular weight fatty acid soap forming materials, from 0.2 to 5% ofmonobasic fatty acids of not, over. 6 carbon atoms, from 1 to 7% ofmontan wax, from 0.95 to 6.5% oflime flour, a

the remainder being lubricating oil.

'9. An improved lime base grease composition characterized by stabilityat temperatures in excess of 200 produced by compounding together- 10.An improved lime base, grease composition characterized by stability attemperatures its in excess of 200 F. produced by compounding together-Per cent Hydrogenated fatty acids 5.5 Cottonseed fatty acids 5.5 Refinedmontan wax 2.0

Low molecular weight organic acids having the general formula CnHznOz,where n is preferably 6 or less, e. g., acetic acid 2.0 Lime flour 3.4100" parafiln oil 81.6

, suificient to give high temperature stability.

aromas 12. An improved lime base grease composition characterized bystability at temperatures of approximately 300 F. comprising lubricatingoil and lime soaps of fatty acids and in addition thereto smallproportions of calcium soaps of montan wax acids and of monobasic fattyacids having not more than 6 carbon atoms, the grease being dehydratedto a degree suflicient to give high temperature stability.

13. An improved lime base grease composition characterized by stabilityat temperatures of approximately 300" F. comprising lubricating oil andlime soaps of fatty acids and in addition thereto small proportions ofcalcium salts of acetic acid and of montan wax acids, the grease beingdehydrated to a degree sufflcient to give high temperature stability.

EMME'I'I S. CARMICHAEL. GEORGE M. HAIN.

